Field of the Invention
The present invention relates to an immediate hot-water supplying system having a function of supplying hot water as soon as a hot-water tap is opened.
Description of the Related Art
An immediate hot-water supplying system has been known, which includes a supply pipe having one end connected to a waterworks and the other end connected to a hot-water tap, a plurality of hot water supply devices which are connected in the midway of the supply pipe and configured to heat water flowing through the supply pipe, a return pipe configured to bypass these hot water supply devices and connect the supply pipe, and a circulation pump configured to circulate water in a circulation circuit including the supply pipe and the return pipe (e.g., refer to Japanese Patent Laid-Open No. 2004-286397).
In the immediate hot-water supplying system described in the above publication, a circulation heat keeping operation is performed when the hot-water tap is closed and the supply of water is stopped, the circulation heat keeping operation in which water flowing through the hot water supply devices is heated while a circulation pump is activated and circulates the water in the circulation circuit. In such a manner, the immediate hot-water supplying system is configured to perform the circulation heat keeping operation to maintain the temperature of the water in the circulation circuit at around a set temperature, so as to supply hot water from the hot-water tap as soon as a user open the hot-water tap.
In addition, the immediate hot-water supplying system is configured to stop the circulation pump when hot water is supplied from the hot-water tap (in a hot-water supplying state). For this reason, in order to detect the hot-water supplying state, the immediate hot-water supplying system includes a first flow amount sensor configured to detect the flow amount of water flowing through the supply pipe, a second flow amount sensor configured to detect the flow amount of water flowing through the return pipe, and a third temperature sensor provided at a merging point of the water supply pipe and the return pipe.
Then, (a) when the detected temperature of the third temperature sensor rapidly decreases, and (b) when a difference between the flow amount detected by the first flow amount sensor and the flow amount detected by the second flow amount sensor becomes equal to or more than a predetermined flow amount, the circulation pump is stopped.
As described above, in the conventional immediate hot-water supplying system, the action of the circulation pump is typically stopped in the hot-water supplying state. Then, in the case of the inclusion of the second flow amount sensor configured to detect the flow amount of water flowing through the return pipe and the third temperature sensor provided at the merging point of the return pipe and the water supply pipe only to detect that it is in the hot-water supplying state, like the immediate hot-water supplying system, there is a disadvantage in that components are increased, which complicates a system configuration and increases a system cost.
The present invention has been made in view of the above background, and has an object to provide an immediate hot-water supplying system which can detect being in a hot-water supplying state without providing a dedicated sensor.